In recent years, the endorectal pull-through has become an attractive alternative approach to the surgical management of ulcerative colitis and familial polyposis since it eliminates the need for a permanent abdominal stoma. At the present time, significant controversy exists as to whether adding a reservoir to the pull-through reduces the postoperative stool frequency and improves the overall results. The purpose of this project is to compare the straight endorectal pull-through with the three commonly employed reservoirs, namely, the "J" pouch, the "S" pouch and the lateral ileal reservoir. Twenty-four conditioned Beagle puppies will be used in this study, six animals in each group. A comprehensive physiological evaluation of the four pull-throughs will be conducted. The following tests will be used to monitor the physiological changes in the animal groups before and after each pull-through operation: rectal manometry, water and electrolyte absorption, stool bacterial flora distribution, stool fecal fat concentration, twenty-four hour stool frequency, intestinal transit time, observation of the intestinal reservoir by endoscopy and pathological evaluation of the pull-through ileal mucosa. A comparison of these physiological parameters among the four animal groups will help provide information about whether or not a reservoir is useful with a pull-through procedure, and, if so, which reservoir appears to be most effective.